Heavy cannabis users were slower at recognizing facial emotions | Research

The takeaway

Heavy cannabis users were significantly slower than controls at identifying sadness, anger, and happiness in dynamic facial expressions, requiring greater emotional intensity before recognition.

Read this if you are interested in how heavy cannabis use might affect social skills and emotional awareness.

Slower emotion recognition across all three tested emotions

What the researchers found

Researchers compared emotion recognition between heavy cannabis users and non-using controls using dynamic facial expressions that gradually changed from neutral to increasingly intense emotional displays.

Cannabis users were significantly slower at identifying all three emotional expressions (sadness, anger, and happiness). This was not due to general cognitive slowing, as users showed no delay in identifying neutral-to-neutral facial changes.

Cannabis users also had a more liberal response criterion for recognizing sadness, meaning they were more likely to identify an expression as sad even at low intensities.

The findings suggested a generalized deficit in reading basic emotions during social interactions.

Why it matters

Difficulty reading emotions in others could contribute to interpersonal problems reported by cannabis users and may relate to the observed association between heavy cannabis use and mental health difficulties.

The numbers in context

Cannabis users were significantly slower at identifying all three emotional expressions. No difference in neutral-to-neutral recognition speed, ruling out general cognitive slowing.

How the study worked

Cross-sectional study comparing heavy cannabis users to non-using controls on a dynamic emotion recognition task. Facial expressions morphed from neutral to increasingly intense emotions. Reaction times and accuracy were recorded. Participants also completed measures of theory of mind, depression, and impulsivity.

What this study cannot tell us

Cross-sectional design cannot determine whether cannabis caused the deficits or whether people with existing emotion recognition difficulties were more likely to use cannabis heavily. The study did not control for all potential confounders.

How to read the evidence

Cross-sectional study with appropriate controls (neutral-to-neutral condition) but unable to establish causation.

When this study was published

Published in 2010. Research on cannabis and social cognition has continued to develop.

The bigger picture

These findings connected cannabis use to social cognition deficits, expanding the understanding of cannabis effects beyond traditional cognitive domains like memory and attention.

Questions still open

Would these emotion recognition deficits recover with sustained abstinence? Do they contribute to the social isolation sometimes observed in heavy cannabis users?

Common questions

Does cannabis make it harder to read people's emotions?

This study found heavy cannabis users needed stronger emotional intensity before recognizing facial expressions, but could not determine whether cannabis caused this or whether the deficit existed before use began.

Was this just because cannabis users were slower in general?

No. Cannabis users were not slower at recognizing neutral facial changes, only emotional ones. This suggests a specific deficit in emotion processing rather than general cognitive slowing.

Read the original research

Processing dynamic facial affect in frequent cannabis-users: evidence of deficits in the speed of identifying emotional expressions.

Drug and alcohol dependence, 112(1-2), 27-32

View on PubMed ↗Publisher’s paper ↗

Citation

Platt, Bradley; Kamboj, Sunjeev; Morgan, Celia J A; Curran, H Valerie. (2010). Processing dynamic facial affect in frequent cannabis-users: evidence of deficits in the speed of identifying emotional expressions.. Drug and alcohol dependence, 112(1-2), 27-32. https://doi.org/10.1016/j.drugalcdep.2010.05.004